That is a hybrid SACD, and a 3.0 disc from what I found on it. The CD layer would be purely 2.0 (and there is one, as it's a hybrid), but the Denon would be playing the SACD layer. My first thought is rather simple - the 80Hz crossover will only provide a signal for the sub when there is material present below 80hz in the recording (no LFE track), and I have no idea just how much content of this type may exist in the recording.